The present invention relates generally to an air pump structure capable of reciprocating pumping action, and more particularly to a compact air pump structure capable of simultaneous pumping and intake in a single travel, whereby pumping efficiency is enhanced and pumping time is reduced.
The conventional air pump mainly consists of a piston, a pressing element, a cylinder having an air inlet and an air outlet at suitable postions thereon, an air tap and relevant tubings. The air inlet and outlet of the cylinder both function in a single direction. The piston is fitted closely inside the cylinder in which it moves up or down due to linking-up with the pressing element. When the piston is moved downward by means of the pressing element, the air inside the cylinder is pressed by the piston through the air outlet, tubes and air tap into the tire. When the piston travels backward, due to the pulling action of the piston, the pressure inside the cylinder is less than the atmospheric pressure, then the air outside enters through the air inlet to refill the cylinder.
From the above-described conventional air pump structure and the way of pumping, it can be seen that the piston can only do the work of pumping air into the tire in one travel, and does not perform any work on its return travel, other than the intake of air due to the difference in air pressures. In this structure, the pumping efficiency is low and the pumping time is prolonged. Elimination of these drawbacks in conventional air pumps is therefore necessary.